Finger-Jointed Studs

Q.Can finger-jointed studs be
used for wall plates and short window and door
headers?

A.Paul Fisette, director
of Building Materials and Wood Technology at the
University of Massachusetts Amherst and a JLC
contributing editor, responds: Besides being
resource-efficient, the use of finger-jointed wall
framing provides straighter, better walls
— but if your studs are rated "for
vertical use only," then the short answer is
no.

While the IRC (2006, R602.1.1) allows graded
finger-jointed lumber to be used interchangeably
with solid-sawn members of the same species and
grade, "for vertical use only" means this
engineered product is equivalent to "stud"-grade
lumber (the grade stamp should also indicate
"stud"). Stud-grade lumber can have knots and other
strength-reducing characteristics that compromise
performance under bending stresses but not in
compression. Both finger-jointed and sawn studs are
strong enough for short-term bending or tension
loads (from wind, earthquakes, and impact, for
instance), but not for long-term exposure.

Practically speaking, continuously supported
bottom plates and top plates with upper-level
joists or rafters oriented directly over studs are
not subject to continuous bending loads, so you
could try to seek approval for this use of
stud-grade lumber on a case-by-case basis from your
building inspector. But the material is not meant
for this purpose, and it comes in only 10- and
12-feet lengths, which is not ideal for most plate
applications. If you want to use finger-jointed top
plates, it's better to specify structural
finger-jointed lumber (labeled "CERT EXT
JNTS").

A final caveat: Finger-jointed studs can't be
used in fire-rated assemblies unless they are
labeled HRA (heat-resistant adhesive).